Soft magnetic metals generally refer to metals that have a low coercive force and have the property of demonstrating a large reduction in residual magnetism due to removal of an external magnetic field.
In recent years, soft magnetic metal particles have come to be used in various fields, such as the formation of coated films wherein paints are prepared by dispersing these particles in an organic binder in the form of magnetic pigments and then these paints are coated onto a substrate and the like to form a coated films, or the production of soft magnetic metal/resin composites wherein metal particles are dispersed in a binder in the form of a magnetic filler to form the composites.
An example of a coated film that uses soft magnetic metal particles is a magnetic shielding film. This magnetic shielding film is used to protect electronic circuits and electronic components of electrical devices from external magnetic fields, or prevent leakage of magnetic fields generated by electrical devices to the outside. In addition, this magnetic shielding film is also used for the purpose of preventing forgery or falsification of data contained in magnetic cards such as credit cards. Moreover, coated films using such soft magnetic metals are also used in IC tags (RFID systems) as magnetic sheets, which can improve sensitivity, by applying magnetic field convergence effects attributable to the high magnetic permeability of soft magnetic metals.
On the other hand, soft magnetic metal/resin composites using soft magnetic metals are used in high-frequency electronic circuit substrates since the composites enable the power consumption of electronic circuits to be reduced.
High magnetic permeability alloys such as Al—Si—Fe-based alloy commonly referred to as Sendust alloy (see, for example, Patent Document 1) or Ni—Fe-based alloy commonly referred to as PERMALLOY (trade name) (see, for example, Patent Document 2) are used as such soft magnetic metals.
In addition, soft magnetic metal particles are typically required to have the tabular form having a thickness of 1 μm or less. More specifically, soft magnetic metal particles of various tabular shapes have been proposed, such as flat-shaped, scale-shaped and flake-shaped particles (see, for example, Patent Documents 1 to 3).
These tabular soft magnetic metal particles are able to enhance the smoothness of the surface of coated films and soft magnetic particle/resin composites containing these particles. In addition, when a paint containing tabular soft magnetic metal particles is coated or when a soft magnetic metal/resin composite containing tabular soft magnetic metal particles is formed, the particles can align (orient) in parallel with a specific direction as a result of being subjected to an external magnetic field. Thus, due to orientation, together with lowering the demagnetizing coefficient in the planar direction of a coated film or soft magnetic metal/resin composite, magnetic permeability in the direction in which the soft magnetic metal particles are aligned can be enhanced.
In addition, since tabular soft magnetic metal particles have a thickness of 1 μm or less, they allow the passage of alternating current due to skin effects, thereby making it possible to reduce loss attributable to eddy current.
These tabular soft magnetic metal particles are typically produced by subjecting irregularly shaped particles produced by atomization to mechanical pulverization or plastic deformation.    Patent Document 1: Japanese Unexamined Patent Application, First Publication No. S63-35701    Patent Document 2: Japanese Patent No. 2735615    Patent Document 3: Japanese Unexamined Patent Application, First Publication No. H1-188606    Non-Patent Document 1: JCPDS Card 04-0850    Non-Patent Document 2: JCPDS Card 88-1715